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AS · Practice questions · The internet and the world wide web

Stream it smoothly.

Six original Cambridge-style questions on the internet, the web and bit streaming, with mark-scheme style solutions.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Hardware versus service.

01
Explain
[3 marks]

Explain the difference between the internet and the World Wide Web.

  • The internet is a global network of interconnected networks / the infrastructure (cables, routers). ✓
  • The WWW is a collection of web pages and resources linked by hyperlinks, accessed using HTTP(S) and a browser. ✓
  • The WWW is one service that runs over the internet (others include email and file transfer). ✓
02
Recall
[4 marks]

Describe the role of each of the following in supporting the internet: (a) modem (b) PSTN (c) dedicated line (d) cell phone network.

  • (a) Converts digital signals to analogue for transmission over a telephone line, and analogue back to digital. ✓
  • (b) The public telephone network of lines and exchanges, which also carries internet data (dial-up/broadband). ✓
  • (c) A permanent, private (leased) connection between two points with guaranteed bandwidth. ✓
  • (d) Gives mobile devices internet access by radio through base stations / masts in each cell. ✓
03
Explain
[4 marks]

Explain the difference between real-time and on-demand bit streaming, giving an example of each.

  • Real-time: the event is encoded and streamed live as it happens. ✓
  • Example: a live sports match / a video call. ✓
  • On-demand: a pre-recorded file is stored on a server and streamed when the user requests it; the user can pause, rewind and skip. ✓
  • Example: a film from a streaming library / a podcast. ✓
04
Calculate
[3 marks]

A lesson recording is streamed at 2.5 Mbps and lasts 30 minutes. Calculate the amount of data transferred in megabytes. Use 1 Mbps = 1 000 000 bits per second and 1 MB = 1 000 000 bytes. Show your working.

  • 30 minutes = 1800 seconds. ✓
  • 2 500 000 × 1800 = 4 500 000 000 bits. ✓
  • ÷ 8 = 562 500 000 bytes = 562.5 MB. ✓
05
Explain
[3 marks]

Explain the purpose of a buffer when streaming video.

  • Data received is stored temporarily in the buffer (memory) before it is played. ✓
  • Playback is taken from the buffer, so short drops in the connection speed do not interrupt the video. ✓
  • Playback only pauses if the buffer empties because data arrives more slowly than it is played. ✓
06
Analysis
[3 marks]

A household has a 25 Mbps connection. A 4K video stream needs 15 Mbps and an HD stream needs 5 Mbps. One person watches 4K while two others each watch HD. Will all three play smoothly? Explain.

  • Total bit rate needed: 15 + 5 + 5 = 25 Mbps. ✓
  • This equals the full 25 Mbps available, with no spare capacity for other traffic or drops in speed. ✓
  • So the streams are likely to buffer at times (or the services will reduce quality); they may only just play smoothly. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.